Feedback we have received a fair amount about is that Windows Live Writer 2011 does not work with Paint.NET whereas the previous version of Live Writer worked fine. Anything copied from Paint.NET and pasted in Writer would do nothing in 2011. About a week ago Paint.Net produced an update that now works with Live Writer 2011. Go download build
3.6.5 3.5.6 or later of Paint.NET and you should be able to copy and paste those images right into your favorite blogging application.
Update: I had the build number wrong. It is 3.5.6, not 3.6.5.